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TiDB Lightning Monitoring

Both tidb-lightning and tikv-importer supports metrics collection via Prometheus. This document introduces the monitor configuration and monitoring metrics of TiDB Lightning.

Monitor configuration

  • If TiDB Lightning is installed using TiDB Ansible, simply add the servers to the [monitored_servers] section in the inventory.ini file. Then the Prometheus server can collect their metrics.
  • If TiDB Lightning is manually installed, follow the instructions below.

tikv-importer

tikv-importer v2.1 uses Pushgateway to deliver metrics. Configure tikv-importer.toml to recognize the Pushgateway with the following settings:

[metric]

# The Prometheus client push job name.
job = "tikv-importer"

# The Prometheus client push interval.
interval = "15s"

# The Prometheus Pushgateway address.
address = ""

tidb-lightning

The metrics of tidb-lightning can be gathered directly by Prometheus as long as it is discovered. You can set the metrics port in tidb-lightning.toml:

[lightning]
# HTTP port for debugging and Prometheus metrics pulling (0 to disable)
pprof-port = 8289

...

You need to configure Prometheus to make it discover the tidb-lightning server. For instance, you can directly add the server address to the scrape_configs section:

...
scrape_configs:
  - job_name: 'tidb-lightning'
    static_configs:
      - targets: ['192.168.20.10:8289']

Grafana dashboard

Grafana is a web interface to visualize Prometheus metrics as dashboards.

If TiDB Lightning is installed using TiDB Ansible, its dashboard is already installed. Otherwise, the dashboard JSON can be imported from https://raw.githubusercontent.com/pingcap/tidb-ansible/master/scripts/lightning.json.

Row 1: Speed

Panels in first row

PanelSeriesDescription
Import speedwrite from lightningSpeed of sending KVs from TiDB Lightning to TiKV Importer, which depends on each table's complexity
Import speedupload to tikvTotal upload speed from TiKV Importer to all TiKV replicas
Chunk process durationAverage time needed to completely encode one single data file

Sometimes the import speed will drop to zero allowing other parts to catch up. This is normal.

Row 2: Progress

Panels in second row

PanelDescription
Import progressPercentage of data files encoded so far
Checksum progressPercentage of tables are verified to be imported successfully
FailuresNumber of failed tables and their point of failure, normally empty

Row 3: Resource

Panels in third row

PanelDescription
Memory usageAmount of memory occupied by each service
Number of Lightning GoroutinesNumber of running goroutines used by TiDB Lightning
CPU%Number of logical CPU cores utilized by each service

Row 4: Quota

Panels in fourth row

PanelSeriesDescription
Idle workersioNumber of unused io-concurrency, normally close to configured value (default 5), and close to 0 means the disk is too slow
Idle workersclosed-engineNumber of engines which is closed but not yet cleaned up, normally close to index + table-concurrency (default 8), and close to 0 means TiDB Lightning is faster than TiKV Importer, which will cause TiDB Lightning to stall
Idle workerstableNumber of unused table-concurrency, normally 0 until the end of process
Idle workersindexNumber of unused index-concurrency, normally 0 until the end of process
Idle workersregionNumber of unused region-concurrency, normally 0 until the end of process
External resourcesKV EncoderCounts active KV encoders, normally the same as region-concurrency until the end of process
External resourcesImporter EnginesCounts opened engine files, should never exceed the max-open-engines setting

Row 5: Read speed

Panels in fifth row

PanelSeriesDescription
Chunk parser read block durationread blockTime taken to read one block of bytes to prepare for parsing
Chunk parser read block durationapply workerTime elapsed to wait for an idle io-concurrency
SQL process durationrow encodeTime taken to parse and encode a single row
SQL process durationblock deliverTime taken to send a block of KV pairs to TiKV Importer

If any of the duration is too high, it indicates that the disk used by TiDB Lightning is too slow or busy with I/O.

Row 6: Storage

Panels in sixth row

PanelSeriesDescription
SQL process ratedata deliver rateSpeed of delivery of data KV pairs to TiKV Importer
SQL process rateindex deliver rateSpeed of delivery of index KV pairs to TiKV Importer
SQL process ratetotal deliver rateThe sum of two rates above
Total bytesparser read sizeNumber of bytes being read by TiDB Lightning
Total bytesdata deliver sizeNumber of bytes of data KV pairs already delivered to TiKV Importer
Total bytesindex deliver sizeNumber of bytes of index KV pairs already delivered to TiKV Importer
Total bytesstorage_size / 3Total size occupied by the TiKV cluster, divided by 3 (the default number of replicas)

Row 7: Import speed

Panels in seventh row

PanelSeriesDescription
Delivery durationRange deliveryTime taken to upload a range of KV pairs to the TiKV cluster
Delivery durationSST deliveryTime taken to upload an SST file to the TiKV cluster
SST process durationSplit SSTTime taken to split the stream of KV pairs into SST files
SST process durationSST uploadTime taken to upload an SST file
SST process durationSST ingestTime taken to ingest an uploaded SST file
SST process durationSST sizeFile size of an SST file

Monitoring metrics

This section explains the monitoring metrics of tikv-importer and tidb-lightning, if you need to monitor other metrics not covered by the default Grafana dashboard.

tikv-importer

Metrics provided by tikv-importer are listed under the namespace tikv_import_*.

  • tikv_import_rpc_duration (Histogram)

    Bucketed histogram for the duration of an RPC action. Labels:

    • request: what kind of RPC is executed
      • switch_mode — switched a TiKV node to import/normal mode
      • open_engine — opened an engine file
      • write_engine — received data and written into an engine
      • close_engine — closed an engine file
      • import_engine — imported an engine file into the TiKV cluster
      • cleanup_engine — deleted an engine file
      • compact_cluster — explicitly compacted the TiKV cluster
      • upload — uploaded an SST file
      • ingest — ingested an SST file
      • compact — explicitly compacted a TiKV node
    • result: the execution result of the RPC
      • ok
      • error
  • tikv_import_write_chunk_bytes (Histogram)

    Bucketed histogram for the uncompressed size of a block of KV pairs received from Lightning.

  • tikv_import_write_chunk_duration (Histogram)

    Bucketed histogram for the time needed to receive a block of KV pairs from Lightning.

  • tikv_import_upload_chunk_bytes (Histogram)

    Bucketed histogram for the compressed size of a chunk of SST file uploaded to TiKV.

  • tikv_import_upload_chunk_duration (Histogram)

    Bucketed histogram for the time needed to upload a chunk of SST file to TiKV.

  • tikv_import_range_delivery_duration (Histogram)

    Bucketed histogram for the time needed to deliver a range of KV pairs into a dispatch-job.

  • tikv_import_split_sst_duration (Histogram)

    Bucketed histogram for the time needed to split off a range from the engine file into a single SST file.

  • tikv_import_sst_delivery_duration (Histogram)

    Bucketed histogram for the time needed to deliver an SST file from a dispatch-job to an ImportSSTJob.

  • tikv_import_sst_recv_duration (Histogram)

    Bucketed histogram for the time needed to receive an SST file from a dispatch-job in an ImportSSTJob.

  • tikv_import_sst_upload_duration (Histogram)

    Bucketed histogram for the time needed to upload an SST file from an ImportSSTJob to a TiKV node.

  • tikv_import_sst_chunk_bytes (Histogram)

    Bucketed histogram for the compressed size of the SST file uploaded to a TiKV node.

  • tikv_import_sst_ingest_duration (Histogram)

    Bucketed histogram for the time needed to ingest an SST file into TiKV.

  • tikv_import_each_phase (Gauge)

    Indicates the running phase. Possible values are 1, meaning running inside the phase, and 0, meaning outside the phase. Labels:

    • phase: prepare/import
  • tikv_import_wait_store_available_count (Counter)

    Counts the number of times a TiKV node is found to have insufficient space when uploading SST files. Labels:

    • store_id: The TiKV store ID.

tidb-lightning

Metrics provided by tidb-lightning are listed under the namespace lightning_*.

  • lightning_importer_engine (Counter)

    Counts open and closed engine files. Labels:

    • type:
      • open
      • closed
  • lightning_idle_workers (Gauge)

    Counts idle workers. Labels:

    • name:
      • table — the remainder of table-concurrency, normally 0 until the end of the process
      • index — the remainder of index-concurrency, normally 0 until the end of the process
      • region — the remainder of region-concurrency, normally 0 until the end of the process
      • io — the remainder of io-concurrency, normally close to configured value (default 5), and close to 0 means the disk is too slow
      • closed-engine — number of engines which have been closed but not yet cleaned up, normally close to index + table-concurrency (default 8). A value close to 0 means TiDB Lightning is faster than TiKV Importer, which might cause TiDB Lightning to stall
  • lightning_kv_encoder (Counter)

    Counts open and closed KV encoders. KV encoders are in-memory TiDB instances that convert SQL INSERT statements into KV pairs. The net values need to be bounded in a healthy situation. Labels:

    • type:
      • open
      • closed
  • lightning_tables (Counter)

    Counts processed tables and their statuses. Labels:

    • state: the status of the table, indicating which phase should be completed
      • pending — not yet processed
      • written — all data encoded and sent
      • closed — all corresponding engine files closed
      • imported — all engine files have been imported into the target cluster
      • altered_auto_inc — AUTO_INCREMENT ID altered
      • checksum — checksum performed
      • analyzed — statistics analysis performed
      • completed — the table has been fully imported and verified
    • result: the result of the current phase
      • success — the phase completed successfully
      • failure — the phase failed (did not complete)
  • lightning_engines (Counter)

    Counts number of engine files processed and their status. Labels:

    • state: the status of the engine, indicating which phase should be completed
      • pending — not yet processed
      • written — all data encoded and sent
      • closed — engine file closed
      • imported — the engine file has been imported into the target cluster
      • completed — the engine has been fully imported
    • result: the result of the current phase
      • success — the phase completed successfully
      • failure — the phase failed (did not complete)
  • lightning_chunks (Counter)

    Counts number of chunks processed and their status. Labels:

    • state: a chunk's status, indicating which phase the chunk is in
      • estimated — (not a state) this value gives total number of chunks in current task
      • pending — loaded but not yet processed
      • running — data are being encoded and sent
      • finished — the entire chunk has been processed
      • failed — errors happened during processing
  • lightning_import_seconds (Histogram)

    Bucketed histogram for the time needed to import a table.

  • lightning_row_read_bytes (Histogram)

    Bucketed histogram for the size of a single SQL row.

  • lightning_row_encode_seconds (Histogram)

    Bucketed histogram for the time needed to encode a single SQL row into KV pairs.

  • lightning_row_kv_deliver_seconds (Histogram)

    Bucketed histogram for the time needed to deliver a set of KV pairs corresponding to one single SQL row.

  • lightning_block_deliver_seconds (Histogram)

    Bucketed histogram for the time needed to deliver a block of KV pairs to Importer.

  • lightning_block_deliver_bytes (Histogram)

    Bucketed histogram for the uncompressed size of a block of KV pairs delivered to Importer.

  • lightning_chunk_parser_read_block_seconds (Histogram)

    Bucketed histogram for the time needed by the data file parser to read a block.

  • lightning_checksum_seconds (Histogram)

    Bucketed histogram for the time needed to compute the checksum of a table.

  • lightning_apply_worker_seconds (Histogram)

    Bucketed histogram for the time needed to acquire an idle worker (see also the lightning_idle_workers gauge). Labels:

    • name:
      • table
      • index
      • region
      • io
      • closed-engine